The Dual Role of an ESCRT-0 Component HGS in HBV Transcription and Naked Capsid Secretion.
The Dual Role of an ESCRT-0 Component HGS in HBV Transcription and Naked Capsid Secretion.
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DOI：
10.1371/journal.ppat.1005123
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发表时间：
2015-10
期刊：
影响因子：
6.7
通讯作者：
Shih C
中科院分区：
文献类型：
--
作者：
Chou SF;Tsai ML;Huang JY;Chang YS;Shih C
转运所需的内体分选复合物（ESCRT）是一种重要的细胞机制，用于泛素化货物的分选和运输。还已知ESCRT是许多病毒外出所必需的。为了研究ESCRT与B型肝炎病毒（HBV）之间的关系，我们对ESCRT组分进行了siRNA筛选，以了解它们对HBV复制和病毒粒子释放的潜在影响。我们确定了HBV复制所需的一些ESCRT因子，并将我们的研究集中在ESCRT-0复合物中的HGS（HRS，肝细胞生长因子调节的酪氨酸激酶底物）上。异常水平的HGS抑制HBV转录、复制和病毒体分泌。HGS在小鼠模型中的流体动力学递送显著抑制肝脏中的病毒复制和血清中的病毒体分泌。令人惊讶的是，HGS的过表达刺激了HBV裸衣壳的释放，而不管它们的病毒RNA、DNA或空内容物。突变核心蛋白（HBc 1-147）不含富丝氨酸结构域（ARD）分泌空病毒粒子或不含HGS。相比之下，HBc 1-147的空裸衣壳仍可被HGS促进分泌。HGS对裸露衣壳的分泌产生强烈的积极影响，代价是降低病毒体的水平。HGS和HBc之间的关联似乎是不依赖于泛素的。此外，HBc优先与HGS共定位在细胞周边附近，而不是细胞质中的点状内体附近。总之，我们的工作证明了最佳水平的HGS在HBV传播中的重要性。除了对HBV转录的影响外，HGS还可以随着基因组的不断成熟而减少细胞内核衣壳的池大小，这可能部分是通过促进裸衣壳的分泌。HBV病毒粒子和裸衣壳的分泌途径可以基于ESCRT-0复合物中涉及的HGS的多效性效应来清楚地区分。B型肝炎病毒（HBV）是人类重要的病原体。慢性HBV感染可导致肝硬化和肝癌。虽然HBV感染是可以治疗的，但根除患者体内的病毒仍然是一个挑战。HBV可以产生具有不同大小和形态的各种颗粒。病毒粒子是具有核衣壳和表面抗原（HBsAg）包膜的完整颗粒。除了含有DNA的病毒粒子，HBV产生不完整的颗粒，包括没有核衣壳的HBsAg颗粒，没有HBsAg包膜的裸露衣壳颗粒，以及含有HBsAg包膜和空衣壳的空病毒粒子。目前尚不清楚这些不同的HBV颗粒是如何从肝脏输出的。我们确定了许多已知参与膜运输机制（所谓的ESCRT）以及HBV复制所需的宿主因子。有趣的是，HGS（一种ESCRT-0因子）的异常表达可以抑制HBV复制。然而，出乎意料的是，HGS可以促进裸衣壳的释放，同时减少细胞外病毒体和HBsAg颗粒。HGS可与HBV衣壳蛋白结合共定位。总之，我们的工作表明，适当水平的HGS对HBV传播是重要的。我们认为HGS和其他ESCRT因子有可能进一步发展成为B型肝炎的治疗手段。
The Endosomal Sorting Complex Required for Transport (ESCRT) is an important cellular machinery for the sorting and trafficking of ubiquitinated cargos. It is also known that ESCRT is required for the egress of a number of viruses. To investigate the relationship between ESCRT and hepatitis B virus (HBV), we conducted an siRNA screening of ESCRT components for their potential effect on HBV replication and virion release. We identified a number of ESCRT factors required for HBV replication, and focused our study here on HGS (HRS, hepatocyte growth factor-regulated tyrosine kinase substrate) in the ESCRT-0 complex. Aberrant levels of HGS suppressed HBV transcription, replication and virion secretion. Hydrodynamic delivery of HGS in a mouse model significantly suppressed viral replication in the liver and virion secretion in the serum. Surprisingly, overexpression of HGS stimulated the release of HBV naked capsids, irrespective of their viral RNA, DNA, or empty contents. Mutant core protein (HBc 1–147) containing no arginine-rich domain (ARD) failed to secrete empty virions with or without HGS. In contrast, empty naked capsids of HBc 1–147 could still be promoted for secretion by HGS. HGS exerted a strong positive effect on the secretion of naked capsids, at the expense of a reduced level of virions. The association between HGS and HBc appears to be ubiquitin-independent. Furthermore, HBc is preferentially co-localized with HGS near the cell periphery, instead of near the punctate endosomes in the cytoplasm. In summary, our work demonstrated the importance of an optimum level of HGS in HBV propagation. In addition to an effect on HBV transcription, HGS can diminish the pool size of intracellular nucleocapsids with ongoing genome maturation, probably in part by promoting the secretion of naked capsids. The secretion routes of HBV virions and naked capsids can be clearly distinguished based on the pleiotropic effect of HGS involved in the ESCRT-0 complex. Hepatitis B virus (HBV) is an important human pathogen. Chronic infection with HBV can lead to cirrhosis and liver cancer. While HBV infection is treatable, it remains a challenge to eradicate the virus in patients. HBV can produce various particles with different sizes and morphologies. Virions are complete particles with both nucleocapsids and surface antigen (HBsAg) envelope. In addition to DNA-containing virions, HBV produced incomplete particles, including HBsAg particles without nucleocapsids, naked capsid particles without the HBsAg envelope, and empty virions containing both HBsAg envelope and empty capsids. It remains unclear how these various HBV particles are exported from the liver. We identified many host factors known to be involved in a membrane trafficking machinery (so-called ESCRT), as well as required for HBV replication. Interestingly, aberrant expression of HGS (an ESCRT-0 factor) can inhibit HBV replication. However, unexpectedly, HGS could boost the release of naked capsids, while concurrently reduced the extracellular virions and HBsAg particles. HGS can associate and co-localize with HBV capsid protein. In summary, our work demonstrated that an appropriate level of HGS is important for HBV propagation. We entertain the possibility that HGS and other ESCRT factors may be further developed into a therapeutic treatment for hepatitis B.